1. Field of the Invention
The present invention relates to a flat color panel cathode ray tube (CRT), and more particularly, to a panel structure and a funnel structure of a flat color panel cathode ray tube (CRT).
2. Description of the Related Art
FIG. 1 is a partial side sectional view illustrating a general color cathode ray tube. Referring to FIG. 1, the general color cathode ray tube will be described.
The CRT includes a front panel 1 and a rear funnel 2. The panel 1 and the funnel 2 are all made of glass, and the rear funnel 2 is coupled with a rear side of the front panel 1. A fluorescent material coats the inner surface of the panel 1 to form a fluorescent surface. The fluorescent surface emits light when struck by an electron beam 11. An electron gun 8 generates the electron beam 11 and is located in a neck 10 of the funnel 2. A shadow mask 3 serves to selectively pass the electron beam 11 so that the electron beam 11 reaches a desired position of the fluorescent surface. This shadow mask 3 is supported by a frame 4 and located in the vicinity of the inner surface of the panel 1. The frame 4 is fixed to the panel 1 by a spring 5 and a pin 6. A deflection yoke 9 is installed on an outer circumference of the funnel 2. The deflection yoke 9 sequentially deflects the electron beam 11 up, down, left, and right. The fluorescent surface struck by the electron beam 11 forms a picture. An inner shield 7 is fixed to the frame 7 so that the travel of the electron 11 is not affected by any external earth magnetic field. Because the inside of the CRT is in a high vacuum state, the CRT is vulnerable to external impact. Accordingly, the panel 1 and the funnel 2 are designed to have enough strength to counter such a vacuum pressure. A reinforcing band 12 is installed on the outer surface of the skirt of the panel 1, and thus the stress that the CRT is subject to under a high vacuum is dispersed.
A CRT is an image display device and has been the most popular display device in various fields. Recently, the CRT has been improved due to technology improvements and customers' requests. Especially the flat panel CRT has been developed to minimize image distortion.
Referring to FIG. 2A, the conventional panel includes an inner surface and an outer surface that have a predetermined curvature. Accordingly, an image is distorted and ambient light is reflected in many directions due to the curvature of the outer surface resulting in degraded viewing capability. To improve the conventional panel, as shown in FIG. 2B, a flat panel that has a substantially flat outer surface has been developed. The flat panel removes the image distortion and lowers eye fatigue, so it has gained widespread use recently.
A more detailed description of the difference between the curved panel and the flat panel will be made with reference to FIG. 3. The half cross-sectional surface of the curved panel is depicted on the right side of FIG. 3 and the half cross-sectional surface of the flat panel is depicted on the left side of FIG. 3.
Typically, the curved panel and the flat panel are manufactured on the same manufacturing line. The curved panel is employed in less expensive CRTs and the flat panel is employed in more expensive CRTs. For convenience, the CRT that has the flat panel is called a ‘flat panel CRT’ and the CRT that has the curved panel is called a ‘curved panel CRT’. Accordingly, to enhance the efficiency of the manufacturing processes, as shown in FIG. 3, the flat panel CRT is designed to have the same panel height as the panel height (OAH: the height distance between the center of the outer surface and the seal edge line of a skirt 1 a coupled with the panel 2) of the curved CRT.
However, due to such a design as shown in drawings, the length of the skirt 1a of the flat panel gets longer. Because the outer surface of the panel 1 is flat but the inner surface of the panel 1 has a curvature, the corner portion 1b gets thicker as compared to the curved panel. Accordingly, the flat panel 1 is heavier than the curved panel 2 by about 10–15%, so that the assembly process for the flat panel CRT becomes more difficult, and its use becomes inconvenient. Also, the flat panel 1 is vulnerable to excess thermal stress in a furnace as the volume and weight increases.